1. Field
Example embodiments relate to ferromagnetic graphenes and spin valve devices, for example, ferromagnetic graphenes including one or more antidots and spin valve devices including ferromagnetic graphenes.
2. Description of the Related Art
A graphene having a 2-dimensional hexagonal carbon structure is a material that may be an alternative to conventional semiconductors. A graphene is a zero-gap semiconductor. Also, because a graphene has a relatively high carrier mobility of about 100,000 cm2V−1s−1 at room temperature, which is about 100 times higher than that of conventional silicon, the graphene may be applied to devices that operate at relatively high speeds (e.g., radio frequency (RF) devices).
If a graphene is cut to have an armchair edge, the graphene is non-magnetic. If a graphene has a zigzag edge, a net magnetic moment is about zero due to antiferromagnetic coupling.
A conventional spin valve device includes two or more conductive magnetic materials, and an electrical resistance of the conventional spin valve device varies according to spin directions of the conductive magnetic materials. In one example, a giant magnetoresistance effect may show this phenomenon. When spins of magnetic material layers are in a parallel alignment, a resistance to electrons passing through the magnetic material layers is relatively low. By contrast, when spins of the magnetic material layers are in an anti-parallel alignment, a resistance to electrons passing through the magnetic material layers is relatively high.
Conventional spin valve devices may be applied to, for example, magnetic sensors, write heads of hard discs, magnetic random access memories (MRAMs), and so on.
In order to utilize a graphene in conventional spin valve devices, the graphene should be ferromagnetic.